You can easily convince yourself a station wagon or an SUV will make your life better, that they're necessities for a modern family. But no one needs a car
like that with 500 hp. You certainly don't need one with 500 hp and track-ready suspension. Of course, no one needs dessert, either. But it makes life
better. And we really, really like high-powered versions of otherwise useful things.

In the interest of science, we laid out this delicious spread at Michigan's GingerMan Raceway on a cold Monday morning. Here we have a Mercedes and a
Porsche, different shapes with similar blueprints: take pedestrian cargo hauler, cram in nutso twin-turbo V-8, upgrade brakes, lower, and add as much wheel
and tire as you can stand.

Both of these cars will make you feel like a kid again. Other people's kids will cower in terror. Your kids, riding in back, will feel like littler kids.
And you might be able to convince the person with whom you had those kids that this is all practical. But we didn't bring these two to a road course to
assess practical. If you're buying one, you're not thinking rationally, so don't worry about how these cars are different from each other. Just smell the
hot brakes, cinch down the child seat, and hold on.

Three shocking things about the Cayenne Turbo: It has 500 hp, more than twice that of Porsche's least-powerful Cayenne. It pulls 0.91 g on the skidpad. It
weighs 5210 pounds. It's extremely quick in every measurable way. And because its mass and height offer an exaggerated sense of motion, it's the most
entertaining thing Porsche currently builds.

Sure, a 911 or a Boxster will out-dance the Cayenne in a corner. The Panamera sedan is big, but it's low to the ground, allowing it to mimic sports-car
behavior without making you question nature or the meaning of life. The Cayenne, though, is designed to do things that it shouldn't be designed to do. And
it does them well.

It seems the higher off the ground a Porsche gets, the more it needs to prove that it is, in fact, still a Porsche. At the same time, the Turbo clings to
the idea that it's an SUV; the air suspension has five ride-height settings, including High I and High II, which are intended for off-roading. It doesn't
know what it is. Or maybe it does and it's in denial.

So this is sporting intention, bordering on sporting insecurity. There's the optional Sport package, which includes brake-based torque vectoring and active
anti-roll bars. Then there's a Sport setting for the active dampers, plus an additional Sport button that acts on the transmission and throttle (when
pressed, it also sets the ride height to Low). Shouldn't the quintessential sports-car maker's sport-utility just be sporty to start with?

The Cayenne goes about its business as if a 4.2-second sprint to 60 mph is everyday stuff. Ditto the 12.7-second quarter-mile. Losing the torque-converter
automatic-exchanging it for, say, the dual-clutch gearbox from the Panamera-might improve on those times; the eight-speed slushbox is occasionally slow to
react and pauses under acceleration. Still, much of our appreciation for the Cayenne was born of respect for what it can do on the track-namely, hang
within three seconds of the Benz's lap time around GingerMan. That's despite significant weight and power disadvantages. Impressive stuff.

On a track, this is a busy thing. The all-wheel-drive system and its various helpers are constantly doing something, even if you're not sure what. So the
Porsche is capable, but it's also less predictable than the Mercedes. There's a feeling of artificial distance, as if the truck knows it's shielding you
from something untoward: Look over here! You're going fast now!

All the while, Porsche Torque Vectoring Plus is using the brakes to work wonders on turn-in. Active dampers are adjusting to the road while active
anti-roll bars keep the truck from dragging its door handles on the pavement. All of that works with tons of rubber on 21-inch wheels to produce even more
skidpad grip than the Mercedes.

But it's still confusing, partly because you can approach a corner the same way twice and get wildly different results. The Cayenne also has a habit of
jumping around under throttle. It's not that the throttle itself is jumpy; the Cayenne's whole back end hops around, seemingly indecisive as to which
corner it should direct asphalt-melting quantities of torque. It's at this point that you realize you're in an SUV. The sensation of reality subsides again
on the straights, and then it's time to hit the brakes.

Hurtling down the straights at GingerMan, we had to constantly remind ourselves that the Cayenne had the brakes to backstop its power, its optional
carbon-ceramic discs unflinchingly hauling it down from almost 120 mph. This is, incidentally, the only SUV available with carbon-ceramic brakes. Don't ask
why; the Cayenne thinks it's a sports car.

The Turbo has the atomic-frog look of all Cayennes, its front bumper shaped a bit like pursed lips. There's one wart on the front end, however; the eye for
the optional active cruise control is hacked into the egg-crate grille like an afterthought. And we could do without the Sport Design package, mainly
because of its bi-plane rear spoiler-on top of the other excesses, it's a little much.

Compared with the Mercedes, the Cayenne has the better interior, despite its center console's case of button pox. (And despite an optional shift lever that
looks like a big, funky alien head.) Smooth black leather below the beltline, a coat of Alcantara on top, and nice bright details in between-it's classy,
comfortable, and feels like a Porsche should. It's also Porsche pricey. The Turbo's base sticker of $109,725 was set to High II here, with an option total
of $40,465. Bigger-ticket items include the $8840 ceramic brakes, a $5320 Premium Package Plus, the $4570 Sport Design package, and $3990 for a high-end
sound system by Burmester. The $650 trailer hitch seemed like a no-brainer by comparison.

And that-towing-is one thing the Cayenne can do that the Mercedes can't. It's rated to tow a considerable amount: the same 7716 pounds as every other
auto-trans Cayenne. (Our trained-as-an-engineer road-test editor chose not to tow his boat 10 miles with it, however, as he was afraid to scratch the
pristine receiver. Our road-test editor is a strange man, but then, this is a strange truck.)

Mercedes has been making fast E-Classes for ages, and equally fast wagon versions for almost as long. It's tradition. This one hits 60 in 3.8 seconds, just
a few tenths off a Porsche 911 Carrera S, an actual sports car. But neither the 911 nor the E63 sedan can match the wagon's 57.4 cubic feet of cargo space.
(Porsche's off-roading identity crisis beats it by just under three cubic feet.) It's the marriage of practicality and insanity that makes the AMG wagon a
glorious, wonderful contradiction. It's the most. It's the everything. It wins by virtue of its mere existence.

But where, you might be asking, is the ML63? Surely AMG's high-po mid-size SUV would be a more sensible opponent for the Cayenne. We'll remind you that
sensible only applies to the number of seats and shapes of these characters. Also, we just plain like the five-door E63 better than its M-class brother. So
there.

It's that kind of emotional decision that leads to the purchase of a 500-hp five-door anyway. There's no better way to spend upwards of $100,000 on a
comfortable cruiser that's ready to eat up a track the moment you arrive. Compared with an ordinary E-class wagon, the E63 is the right amount of
different: The engine is amazing and makes a fantastic noise; the wet-clutch, torque-converter-free, seven-speed automatic feels special; the suspension is
tied down; and the thing just looks killer sitting on sensible-by-comparison 19-inch wheels.

For 2012, the E63 swapped its 6.2-liter, naturally aspirated V-8 for a 5.5-liter twin-turbocharged engine that makes 518 hp and 516 lb-ft of torque. In the
"more than too much is barely enough" category, the E63 we took to GingerMan was outfitted with the AMG Performance pack, which bumps output to 550 hp and
590 lb-ft of torque. It also includes a higher top-speed limiter (186 mph instead of 155), a carbon-fiber engine cover, red paint for the otherwise
unchanged brake calipers, and a nifty Alcantara steering wheel. That adds $6550 to the cost of this $93,305 vehicle. It's worth every penny.

Carbon-ceramic brakes would have been an extra $12,625 here, making the Porsche's stoppers almost seem like a bargain. Would they have made a difference
without killing the Benz's price advantage? Perhaps. As it stood, though, the Mercedes beat the Cayenne's braking distances from both 60 and 80 mph. The
advantage was slight, in spite of the E63 weighing 635 pounds less.

Like the Cayenne Turbo, the E63 uses air springs, but here only on the rear axle. The ride height isn't selectable, although there are three settings for
damper firmness. Plus, it's rear-wheel drive, the better to make drifty sideways nonsense happen.

While the Cayenne has a gathering of the button club on its center console, the E63 keeps the switches and choices to a minimum. A knob lets the driver
choose a shift and throttle calibration-Comfort, Sport, Sport +, or Manual-and there's a button to select from the soft, stiff, and stiffest suspension
modes. Traction and stability get a button, and there's an AMG button that selects a preset transmission and suspension setup. That's it.

That simplicity carries over to the rest of the E's interior. The materials are a step down on many surfaces, especially the hard, inexpensive-seeming door
and lower-dash trim; our test example was dressed up with optional carbon-fiber inlays replacing the standard wood. The Mercedes has amazing seats, mostly
because of active air bladders that keep you in place when cornering. (The massage function didn't hurt.) Our biggest interior gripe: The top of the
steering wheel blocks the top of the speedo and the turn-signal indicators.

Little of that matters, though. The E63 is loud at the right times; its suspension is stiff without being uncomfortable; its steering is alive. And though
it'll bomb down the highway comfortably for days, the E63 wakes up on the track.

Throttle response is near-instant; minimal turbo lag leads to maximum tire rotation. For those so inclined, there's also a launch-control function
(Mercedes calls it Race Start) that will rev the engine and drop the transmission's clutch for a crisp getaway. We were able to improve on its results at
the test track with some simple brake-torqueing, but in any mode, the Benz's transmission shifts more crisply than the Porsche's. It too can be slow,
however, and manual shifts are difficult to time because of the paddles' leisurely reaction. But this is a minor complaint. It's a wagon. That drifts.

In this beast, Mercedes has built a car that we want to drive in any situation. Forever. One staffer said he wanted to buy a gun just to keep anyone from
taking the E63's keys. Another claimed that he wanted his funeral procession to be made up of 100 of these things. These are otherwise sensible guys, but
then, hot station wagons make us think terrible thoughts.

A meeting like this may not happen again; AMG's E is about to go all-wheel drive, and any day now, Porsche is bound to realize that the Cayenne is indeed
an SUV and pull the plug on the whole thing. For this brief moment in automotive time, a seemingly impossible kind of craziness was possible. Our lives are
better for it.